Field of the Invention
This invention relates to bearing structures, and more particularly, to a bearing and support structure used in roller skates of the type used for speed racing.
Brief Description of the Prior Art
In speed racing on roller skates, a portion of the success of the racer can be attributed to the skill, strength and stamina of the racer, and a portion to the particular skate construction which characterizes the skates worn by the racer. In the latter regard, the type of wheel construction used on roller skates, and especially the types of bearings employed in such wheels, is of great importance, since the frictional drag which is offered by the bearing structure to the turning of the wheel is a major factor in the speed which can be attained by the skater.
Efforts have previously been directed to the devising of improved bearing structures for use in speed racing roller skates. Such bearing structures generally must take into account several characteristics of roller skates of the speed skating type. Thus, it has been found that the best material for the construction of the wheels of speed racing roller skates is wood, and a considerable amount of investigation and research has gone into the particular types of woods which function most effectively for this purpose. Since wood is the preferred material of wheel construction in the best speed skates, bearings used to support these wheels on the axles of the skates must take into consideration several properties of wood which impose limitations on the types of bearings which can be employed. Thus, for example, the wooden rollers wear away more rapidly, and get "out of round" more quickly, than would metal wheels, and wooden wheels also tend to undergo cracking or splitting when subject to abusive usage, or even when merely subjected to long periods of usage.
It has also come to be required in most roller skating contexts, including speed racing, that the axles which support the wheels of the skates do not project laterally beyond the outer sides or peripheries of the wheels of the skates so as to expose a relatively sharp gouging or penetrating member which can deface the walls adjacent the rink, or result in injury to persons who may collide with the skater. Moreover, each wheel is generally mounted on its axle in a cantilevered fashion with respect to the point of mechanical support of the axle at the truck which projects downwardly from the foot plates of the skates. The cantilevered mounting arrangement imposes a high bending moment on the axles due to loading of the axles via the wheels mounted thereon at points spaced a significant distance from the inward point of support of each axle at the truck.
One type of bearing structure which has previously been used is one which provides a generally cylindrical sleeve positioned concentrically around the axle and having a large bore extending therethrough which is divided or partitioned by an annular spacer flange which is located substantially midway of the cylindrical sleeve. A large opening is provided through the center of the annular spacer flange to accommodate extension of the axle therethrough. A pair of annular ball bearings are positioned inside the sleeve and on opposite sides of the spacer flange.
In the described bearing structure, the cylindrical sleeve has generally been made shorter in length than the thickness through the wooden wheel which it supports, with the result that incomplete support near the outer end of the wheel at the surface of the bore therethrough has been provided. Less than optimum overall radial support is therefore provided to prevent the wheel getting out of round, and becoming cracked as a result of hard use and stresses acting on the outer periphery of the wheel. Moreover, in the described bearing structure, the generally cylindrical sleeve has not been firmly bonded to the wall of the bore through the wooden wheel which is mounted on the cylindrical sleeve, and separation sometimes occurs which, in extreme circumstances, will even allow the wooden wheel to turn upon the cylindrical sleeve.